it is absolutely billable at your regular rate. You cant bill hours on a machine that is busy billing.

Never work for free. That is not work. It’s a donation.

Build your reel by taking staff gigs until you are ready to venture out on your own.

charge by the hour. This way revisions are on them. If you quote a flat price, make sure they understand it is for x amount of hours and additional hours will cost more.

I still rely on external scopes. I grab whatever monitors suit my suite best. They are just monitors. Go by your scopes.

Unity with Avid is still a viable option but after comparing price points, you may see it’s better to stick with Premiere on a network. All files can still be shared, it’s just not as fast.

I think you may have just run out of drive space, otherwise they would all behave the same.